Thermoplastic resin composition with improved UV resistance

ABSTRACT

Thermoplastic resin composition comprising: (a1) at least one styrene-acrylonitrile copolymer component A1, (a2) at least one acrylonitrile styrene acrylate graft copolymer A2 as impact modifier, (a3) optionally at least one thermoplastic polymer A3 other than components A1 and A2, (b) at least one pigment B, (c) at least one hindered amine UV light stabilizer C, and (d) optionally further polymer additives D, other than components B and C, wherein the UV stabilizing component(s) present in the thermoplastic resin are only hindered amine UV light stabilizer(s) C.

The invention relates to a thermoplastic styrene copolymer resincomposition with improved UV resistance comprising at least onestyrene-acrylonitrile copolymer, at least one acrylonitrile styreneacrylate graft copolymer, at least one pigment and at least one hinderedamine UV light stabilizer. The invention further relates to a method forthe preparation of said thermoplastic resin composition, the use of saidthermoplastic resin composition, and molded articles prepared from saidthermoplastic resin composition.

Acrylonitrile-styrene-acrylates (ASA) are thermoplastic resin materialswith intrinsic UV resistance due to the lack of reactive carbon-carbondouble bonds. However, in order to use such thermoplastic resincompositions in outdoor applications under sometimes harsh conditionssuch as rain and intensive UV exposure by sunlight, UV stabilizers arenecessary. Missing UV stabilization leads to inferior mechanicalproperties such as reduced impact toughness, reduced stress-straincharacteristics, reduced resistance to chemicals, discolorations such asyellowing of the thermoplastic resin composition, loss of transparencyof transparent thermoplastic resin compositions, surface damageresulting in parts of the surface being washed off giving rise toirregular scattering of reflected light, which is perceived aslightening or graying of the thermoplastic resin composition.

In addition, thermoplastic resin compositions often comprise at leastone pigment. The pigments themselves already have a significantinfluence on the UV stability of the thermoplastic resin composition.Especially in the case of iron containing pigments, lower UV resistancecan be observed. This results for example in a larger color shift dE ofthe thermoplastic resin compositions comprising iron pigments observedafter artificial weathering compared to thermoplastic resin compositionscomprising pigments not based on iron.

UV absorbers from the class of hydroxyphenyl-benzotriazoles are wellknown as UV stabilizers for polymers in general. Another class of UVstabilizers is the group of hindered amine lights stabilizers (HALS)used for stabilization of all sorts of polymers. UV stabilizers arecommonly used as mixtures of several classes of UV stabilizers for bestUV stabilization. UV stabilizer mixtures are often selected for thesynergistic effects obtained by combination of UV stabilizers ofdifferent classes.

A general overview on the different aspects of ASA thermoplastic resinsis provided in N. Niessner, Practical Guide to Structures, Propertiesand Applications of Styrenic Polymers; United Kingdom: Smithers RapraTechnology Ltd, 2013, Chapter 4. Thermoplastic resin compositions withimproved resistance to weathering are well known in the art.

US 2016/060446 (Samsung) discloses thermoplastic resin compositionswhich can realize good coloring properties and weathering resistancewhile providing a high quality appearance. This is achieved by applyingboth a UV stabilizer and a UV absorber.

U.S. Pat. No. 4,877,826 discloses weatherable styrenic polymer blendscomprising polyalkylene glycol. However, the polymer blends show lowinitial gloss and only limited weatherability. U.S. Pat. No. 4,692,486discloses a synergistic mixture of low-molecular and high-molecularpolyalkylpiperidines, i.e. mixtures of different HALS as UV stabilizersin polypropylene, polyurethane and polystyrene. DE-A 10316198 teachesternary stabilizer mixtures of different UV stabilizers for use invarious thermoplastic resin compositions. EP-A 2593507 disclosesweathering-resistant styrene copolymer moulding compositions. Differenthigh gloss ASA resin compositions are described each comprising twodifferent HALS and additionally styrene acrylonitrile oligomer. WO2012/007268 relates to stabilized acrylonitrile-styrene-acrylic estermolding compositions comprising different UV stabilizers.

There is however a continuous need for thermoplastic resin compositionswith improved UV resistance. It was one objective of the presentinvention to provide thermoplastic resin compositions which comply withthe above identified technical needs. This was achieved by the presentinvention as described herein below and as reflected in the claims.

The term “copolymer” as used herein describes a polymer which is formedby polymerizing two or more different monomers. The polymer may becomposed of only one linear chain or may be branched. The monomer unitsin the copolymer may be alternating regularly forming an alternatingcopolymer, may repeat periodically forming a periodic copolymer, may bestatistically distributed forming a statistical copolymer, or may formdifferent blocks, forming a block copolymer.

The present invention is described in the following by disclosingvarious aspects of the invention. Combinations of different aspectspertaining to different features are also envisaged. All ratiospresented in wt.-% are based on the total weight of the thermoplasticresin composition unless otherwise indicated.

The invention relates to a thermoplastic resin composition comprising(or consisting of):

-   (a1) at least one styrene-acrylonitrile copolymer component A1,-   (a2) at least one acrylonitrile styrene acrylate graft copolymer A2    as impact modifier,-   (a3) optionally at least one thermoplastic polymer A3, other than A1    and A2,-   (b) at least one pigment B,-   (c) at least one hindered amine UV light stabilizer C, and-   (d) optionally further polymer additives D, other than components B    and C,    wherein the UV stabilizing component(s) present in the thermoplastic    resin are only hindered amine UV light stabilizer(s) C.

In one aspect of the present invention, the thermoplastic resincomposition comprises (or consist of) from 70.0 to 99.4 wt.-% ofcomponents A1, A2, and optionally A3, and from 0.5 to 7.0 wt.-% ofcomponent B, and from 0.1 to 1.5 wt.-% of component C.

In another aspect of the present invention, the thermoplastic resincomposition comprises of from 89.0 to 99.3 wt.-% of A1, A2, andoptionally A3, and from 0.5 to 7.0 wt. % of component B, and from 0.1 to1.5 wt.-% of at least one hindered amine UV light stabilizer C, and from0.1 to 2.5 wt.-% of at least one further polymer additive D. In afurther aspect, component B is present in the range of from 0.7 to 5.0wt.-%. In another aspect, component B is present in the range of from0.8 to 4.0 wt.-%. In another aspect, component B is present in the rangeof from 1.0 to 2.0 wt.-%.

In a further aspect, component C is present in the range of from 0.2 to1.25 wt.-%. In another aspect, component C is present in the range offrom 0.3 to 1.0 wt.-%. In another aspect, component C is present in therange of from 0.4 to 0.8 wt.-%. In another aspect Component D is presentin the range of from 0.2 to 2.0 wt.-%. In a further aspect, component Dis present in the range of from 0.3 to 1.75 wt.-%. In another aspect,component B is present in the range of from 0.7 to 5.0 wt.-% andcomponent C is present in the range of from 0.2 to 1.25 wt.-%.

The styrene-acrylonitrile copolymer A1 and the acrylonitrile styreneacrylate graft copolymer A2 form together the acrylonitrile styreneacrylate terpolymer (ASA). This terpolymer is either used on its own oras blend with for example polyamide (ASA/PA) or with polycarbonate(ASA/PC). The spherical particles of crosslinked acrylate rubber (A2.1)are chemically grafted with styrene acrylonitrile copolymer chains(A2.2), and are embedded as acrylonitrile styrene acrylate graftcopolymer (A2) in a styrene acrylonitrile matrix (A1).

The ratio of styrene-acrylonitrile copolymer A1 to acrylonitrile styreneacrylate graft copolymer A2 is in the range of from 10 wt.-% to 95 wt.-%based of A1 to 90 wt.-% to 5 wt.-% of A2 based on the weight of A1 andA2. In one aspect of the invention, the ration of A1 to A2 is in therange of from 45 wt.-% to 90 wt.-% A1 to 55 wt.-% to 10 wt.-% of A2based on the weight of A1 and A2.

In an aspect of the present invention the copolymer A1 is a rubber freestyrene-acrylonitrile copolymer.

In another aspect of the present invention, the styrene-acrylonitrilecopolymer A1 is prepared from at least one first monomer selected fromthe group consisting of styrene, alpha-methylstyrene, and mixturesthereof, and from a second monomer which is acrylonitrile. In a furtheraspect the styrene-acrylonitrile copolymer A1 comprises at least 10wt.-% based on the total weight of component A1 of styrene. In anotheraspect copolymer A1 comprises at least 50 wt.-% based on the totalweight of component A1 of styrene. In a further aspect copolymer A1comprises at least 60 wt.-% based on the total weight of component A1 ofstyrene. In even another aspect copolymer A1 comprises at least 65 wt.-%based on the total weight of component A1 of styrene.

In one aspect of the present invention, the styrene-acrylonitrilecopolymer component A1 has an acrylonitrile content of from 5 to 35wt.-% based on the total weight of the styrene-acrylonitrile copolymercomponent A1. In another aspect, the styrene-acrylonitrile copolymercomponent A1 has an acrylonitrile content of from 15 to 35 wt.-% basedon the total weight of the styrene-acrylonitrile copolymer component A1.In a further aspect the styrene-acrylonitrile copolymer component A1 hasan acrylonitrile content of from 22 to 35 wt.-% based on the totalweight of the styrene-acrylonitrile copolymer component A1.

In a further aspect of the present invention the styrene-acrylonitrilecopolymer A1 is prepared from 50 to 96 wt.-% based on the total weightof copolymer A1 of styrene and/or alpha-methylstyrene and 4 to 50 wt.-%based on the total weight of copolymer A1 of acrylonitrile. In anotheraspect the styrene-acrylonitrile copolymer A1 is prepared from 60 to 85wt.-% based on the total weight of copolymer A1 of styrene and/oralpha-methylstyrene and 15 to 40 wt.-% based on the total weight ofcopolymer A1 of acrylonitrile. In another aspect thestyrene-acrylonitrile copolymer A1 is prepared from 65 wt. % based onthe total weight of copolymer A1 of styrene and 35 wt.-% based on thetotal weight of copolymer A1 of acrylonitrile.

In one aspect of the present invention the weight average molecularweight M_(w) of the styrene-acrylonitrile copolymer A1 ranges of from20,000 to 200,000 g/mol. In another aspect the intrinsic viscosity [η]of the styrene-acrylonitrile copolymer A1 is of from 20 to 110 ml/g,determined in dimethylformamide (DMF) at 25° C. In another aspect theviscosity number VN of the styrene-acrylonitrile copolymer A1 is of from50 to 100 cm³/g determined according to DIN 53726. In even anotheraspect, the viscosity number is in the range of from 55 to 85 cm³/g.

The synthesis of styrene-acrylonitrile copolymers A1 is for exampledescribed in DE-A 24 20 358 and DE-A 27 24 360. Styrene-acrylonitrilecopolymers are also described in DE-A 1 971 3509.

The copolymer A1 can be prepared according to the methods known in theart such as by radical polymerization, for example by emulsionpolymerization, suspension polymerization, polymerization in solution orpolymerization in mass.

The acrylonitrile styrene acrylate graft copolymer A2 comprisesspherical particles of crosslinked acrylate rubber A2.1 that arechemically grafted with styrene acrylonitrile copolymer chains A2.2.

In one aspect of the invention, the acrylonitrile styrene acrylate graftcopolymer A2 comprises of from 50 to 90 wt.-% based in the total weightof A2 of spherical particles of crosslinked acrylate rubber graft baseA2.1 and of from 10 to 50 wt.-% based on the total weight of A2 of graftof styrene acrylonitrile copolymer chains A2.2

The acrylate rubber graft base A2.1 may comprise

-   -   (i) of from 70 to 99.9 wt.-% based on the total weight of A2.1        of at least one C₁ to C₈-alkyl(meth)acrylate,    -   (ii) of from 0 to 29.5 wt.-% based on the total weight of A2.1        of at least one further monomer selected from the group        consisting of styrene, alpha-methylstyrene, C₁- to        C₄-alkylstyrene, acrylonitrile, methacrylonitrile, isoprene,        butadiene, chloroprene, methylmethacrylate,        alkylenglycoledi(meth)acrylate, and vinylmethylether; and    -   (iii) of from 0.1 to 10 wt.-% based on the total weight of A2.1        of at least one di- or polyfunctional crosslinking agent.

The graft of styrene acrylonitrile copolymer chains A2.2 may comprise

-   -   (iv) of from 50 to 100 wt.-% based on the total weight of the        graft A2.2 of at least one monomer selected from the group        consisting of styrene, alpha-methylstyrene, p-methylstyrene, C₁-        to C₄-alkyl(meth)acrylate, and    -   (v) of from 0 to 50 wt.-% based on the total weight of the graft        A2.2 of at least one monomer selected from the group consisting        of acrylonitrile, methacrylnitril, acrylamide, vinylmethyl        ether, anhydrides of unsaturated carboxylic acids such as maleic        acid anhydride, phthalic acid anhydride, and imides of        unsaturated carboxylic acids such as N-cyclohexylmaleimide and        N-phenylmaleimide.

In one aspect of the present invention, component A2 comprise a graftbase A2.1 of from 40 to 90 wt.-% based on the total weight of theimpact-modified graft rubber acrylonitrile styrene acrylate A2comprising

-   (i) from 70 to 99.9 wt.-% of n-butyl acrylate based on the total    weight of A2.1,-   (ii) from 0 to 30 wt.-% of styrene based on the total weight of    A2.1,-   (iii) from 0.1 to 5 wt.-% of a crosslinking agent based on the total    weight of A2.1; and a graft A2.2 of from 10 to 60 wt.-% comprising-   (iv) from 65 to 95 wt.-% based on the total weight of A2.2 of    styrene, and-   (v) from 5 to 35 wt.-% based on the total weight of A2.2 of    acrylonitrile.

The term crosslinking agent is to be understood to describe a compoundwith at least two double bonds, for example chemically different doublebonds, such as one acrylic double bond. In one aspect of the presentinvention the crosslinking agent is selected from the group consistingof allyl(meth)acrylate, divinylbenzene, diallylmaleate, diallylfumarate,diallylpthalate, triallylcyanurat, triallylisocyanurat, anddicyclopentadienyl acrylate. In another aspect of the present inventionthe crosslinking agent is allyl methacrylate (AMA) and/ordicyclopentadienyl acrylate (DCPA).

In another aspect of the present invention the graft base A2.1 comprisesof from 90 to 99.9 wt.-%, based on the total weight of the graft baseA2.1, of n-butyl acrylate. In a further aspect, the graft base A2.1comprises of from 1 to 10 wt.-%, based on the total weight of the graftbase A2.1, of styrene. In another aspect the graft base A2.1 comprisesof from 0.1 to 2.5 wt.-% of a crosslinking agent based on the totalweight of A2.1. In a further aspect the graft base A2.1 comprises offrom 0.4 to 2.1 wt.-% of a crosslinking agent based on the total weightof A2.1.

In another aspect of the present invention, the average particle sized₅₀ of the acrylonitrile styrene acrylate graft copolymer A2, determinedusing an ultracentrifuge, is generally of from 50 to 1000 nm. In afurther aspect the average particle size d₅₀ of the acrylonitrilestyrene acrylate graft copolymer A2 is of from 60 to 850 nm. In anotheraspect the average particle size d₅₀ of the acrylonitrile styreneacrylate graft copolymer A2 is of from 90 to 700 nm. In even anotheraspect the average particle size d₅₀ of the acrylonitrile styreneacrylate graft copolymer A2 is particularly of from 70 to 700 nm. In afurther aspect of the present invention, the acrylonitrile styreneacrylate graft copolymer A2 comprises different particles with differentmean particle diameters, one acrylonitrile styrene acrylate graftcopolymer A2 having a mean particle diameter d₅₀ of from 50 to 180 nm,and a second acrylonitrile styrene acrylate graft copolymer A2 having amean particle diameter d₅₀ of from 200 to 800 nm.

In another aspect the acrylonitrile styrene acrylate graft copolymer A2comprises one acrylonitrile styrene acrylate graft copolymer A2 having amean particle diameter d₅₀ of from 80 to 150 nm, and a secondacrylonitrile styrene acrylate graft copolymer A2 having a mean particlediameter d₅₀ of from 300 to 700 nm. In one aspect of the presentinvention, the different acrylonitrile styrene acrylate graft copolymersA2 are prepared by individually grafting different graft bases A2.1 withthe different grafts A2.2. In even another aspect the acrylonitrilestyrene acrylate graft copolymer A2 comprises one acrylonitrile styreneacrylate graft copolymer A2 having a mean particle diameter d₅₀ of from90 to 100 nm, and a second acrylonitrile styrene acrylate graftcopolymer A2 having a mean particle diameter d₅₀ of from 400 to 600 nm.In a further aspect one acrylonitrile styrene acrylate graft copolymerA2 is desired to have a narrow particle size distribution Q calculatedfrom (d₉₀-d₁₀)/d₅₀ being less than 0.3. In another aspect Q is less than0.2.

The particle size of latex particles can be controlled during synthesisby suitable means as disclosed for example in DE-A 28 26 925.

Typically mean particle size can be measured by ultracentrifugation asdescribed in W. Scholtan et al., Kolloid-Z. u. Z. Polymere 250, pages782 to 796, 1972 or using Hydrodynamic Chromatigraphy (HDC) as disclosedin W. Wohlleben et al., “Measurement of Particle Size Distribution ofPolymer Latexes”, 2010, Editors: L. Gugliotta, J. Vegam p. 130-153. Themean particle diameter d₅₀ represents the diameter value of the particlesize distribution curve where 50 vol.-% have a larger diameter comparedto the d₅₀ value. In similar way for example the d₉₀ value gives theparticle diameter where 90 vol.-% of all particles have a smallerdiameter.

The mean particle size (mass mean; d_(w)) can also be determined byturbidity measurement as described in Lange, Kolloid-Z. u. Z. Polymere,Band 223, Heft 1.

In a further aspect of the present invention, the thermoplastic resincomposition comprises of from 1 to 70 wt.-% based on the total weight ofcomponents A1 and A2 of at least one thermoplastic polymer A3 selectedfrom polycarbonate (PC), polyamide (PA), and mixtures thereof. Inanother aspect, the thermoplastic resin composition comprises of from 0to 50 wt.-% based on the total weight of the ASA components A1 and A2 ofat least one thermoplastic polymer A3 selected from polycarbonate (PC),polyamide (PA) and mixtures thereof.

In a further aspect of the invention, the thermoplastic resincomposition comprises of from 10 to 50 wt.-% based on the total weightof components A1 and A2 of at least one thermoplastic polymer A3selected from polycarbonate (PC), polyamide (PA), and mixtures thereof.In even another aspect of the invention, the thermoplastic resincomposition comprises of from 20 to 40 wt.-% based on the total weightof components A1 and A2 of at least one thermoplastic polymer A3selected from polycarbonate (PC), polyamide (PA), and mixtures thereof.

In another aspect of the present invention, the thermoplastic polymer A3is selected from the group consisting of polycarbonate (PC), polyamide(PA), and mixtures thereof.

Polycarbonate includes one or more, in another aspect one or two, in afurther aspect one aromatic polycarbonate. Aromatic polycarbonateincludes for example polycondensation products, for example aromaticpolycarbonates, aromatic polyester carbonates. According to theinvention suitable aromatic polycarbonates and/or aromatic polyestercarbonates are known from the literature or may be prepared by processesknown from the literature (for the preparation of aromaticpolycarbonates see, for example, Schnell, “Chemistry and Physics ofPolycarbonates”, Interscience Publishers, 1964 and DE-AS 1 495 626, DE-A2 232 877, DE-A 2 703 376, DE-A 2 714 544, DE-A 3 000 610 and DE-A 3 832396; for the preparation of aromatic polyester carbonates e.g. DE-A 3077 934).

The preparation of aromatic polycarbonates is carried out e.g. byreaction of diphenols with carbonic acid halides, in another aspectphosgene, and/or with aromatic dicarboxylic acid dihalides, in anotheraspect benzenedicarboxylic acid dihalides, by the phase interfaceprocess, optionally using chain terminators, for example monophenols,and optionally using branching agents.

These are trifunctional or more than trifunctional, for exampletriphenols or tetraphenols. A preparation via a melt polymerizationprocess by reaction of diphenols with, for example, diphenyl carbonateis also possible.

In one aspect diphenols are hydroquinone, resorcinol,dihydroxydiphenols, bis(hydroxyphenyl)-C₁-C₅-alkanes,bis-(hydroxyphenyl)-C₅-C₆-cycloalkanes, bis(hydroxyphenyl)ethers,bis-(hydroxyphenyl)sulfoxides, bis-(hydroxyphenyl)ketones,bis(hydroxyphenyl)sulfones andα,α-bis-(hydroxyphenyl)-diisopropyl-benzenes and nucleus-brominatedand/or nucleus-chlorinated derivatives thereof. In a further aspectdiphenols are 4,4′-dihydroxydiphenyl, bisphenol A,2,4-bis-(4-hydroxyphenyl)-2-methylbutane,1,1-bis-(4-hydroxyphenyl)-cyclohexane,1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl sulfone and di-and tetrabrominated or chlorinated derivatives thereof, such as, forexample, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane,2,2-bis-(3,5-dichloro-4-hydroxyphenyl)propane or2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane. In another aspect2,2-bis(4-hydroxyphenyl)-propane (bisphenol A) is used. The diphenolsmay be employed individually or as any desired mixtures. The diphenolsare known from the literature or obtainable by processes known from theliterature.

Chain terminators which are suitable for the preparation of thethermoplastic, aromatic polycarbonates are, for example, phenol,p-chlorophenol, p-tert-butylphenol or 2,4,6-tribromophenol, and alsolong-chain alkylphenols, such as 4-[2-(2,4,4-trimethylpentyl)]-phenol,4-(1,3-tetramethylbutyl)-phenol according to DE-A 2 842 005 ormonoalkylphenols or dialkylphenols having a total of 8 to 20 carbonatoms in the alkyl substituents, such as 3,5-di-tert-butylphenol,p-iso-octylphenol, p-tert-octylphenol, p-dodecylphenol and2-(3,5-dimethylheptyl)-phenol and 4-(3,5-dimethylheptyl)-phenol. Theamount of chain terminators to be employed is in general between of from0.5 mol-% and 10 mol %, based on the sum of the moles of the particulardiphenols employed.

The thermoplastic, aromatic polycarbonates have weight-average molecularweights (M_(W), measured e.g. by ultracentrifuge or scattered lightmeasurement) of from 10.000 to 200.000 g/mol, in another aspect 15.000to 80.000 g/mol, in a further aspect 24.000 to 32.000 g/mol. Thethermoplastic, aromatic polycarbonates may be branched in a knownmanner, and in another aspect by incorporation of from 0.05 to 2.0mol-%, based on the sum of the diphenols employed, of compounds whichare trifunctional or more than trifunctional, for example those havingthree and more phenolic groups. Both homopolycarbonates andcopolycarbonates are suitable.

It is also possible of from 1 to 25 wt.-%, in another aspect 2.5 to 25wt.-%, based on the total amount of diphenols to be employed, ofpolydiorganosiloxanes having hydroxy-aryloxy end groups to be employedfor the preparation of copolycarbonates according to the inventionaccording to component A. These are known (U.S. Pat. No. 3,419,634) andmay be prepared by processes known from the literature. The preparationof copolycarbonates containing polydi-organosiloxanes is described inDE-A 3 334 782. In another aspect polycarbonates are, in addition to thebisphenol A homopolycarbonates, the copolycarbonates of bisphenol A withup to 15 mol-%, based on the sum of the moles of diphenols, of otherdiphenols mentioned, in a further aspect2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane.

Aromatic dicarboxylic acid dihalides for the preparation of aromaticpolyester carbonates are in another aspect the diacid dichlorides ofisophthalic acid, terephthalic acid, di-phenyl ether-4,4′-dicarboxylicacid and of naphthalene-2,6-dicarboxylic acid. Mixtures of the diaciddichlorides of isophthalic acid and of terephthalic acid are in a ratioof from between 1:20 and 20:1. A carbonic acid halide, in another aspectphosgene, is additionally co-used as a bifunctional acid derivative inthe preparation of polyester carbonates. Possible chain terminators forthe preparation of the aromatic polyester carbonates are, in addition tothe monophenols already mentioned, also chlorocarbonic acid estersthereof as well as the acid chlorides of aromatic monocarboxylic acids,which may optionally be substituted by C₁ to C₂₂-alkyl groups or byhalogen atoms, as well as aliphatic C₂ to C₂₂-monocarboxylic acidchlorides. The amount of chain terminators is in each case of from 0.1to 10 mol-%, based on the moles of diphenol in the case of the phenolicchain terminators and on the moles of dicarboxylic acid dichloride inthe case of monocarboxylic acid chloride chain terminators. The aromaticpolyester carbonates may also contain incorporated aromatichydroxycarboxylic acids.

The aromatic polyester carbonates may be either linear or branched in aknown manner (in this context see DE-A 2 940 024 and DE-A 3 007 934).Branching agents which may be used are, for example, carboxylic acidchlorides which are trifunctional or more than trifunctional, such astrimesic acid trichloride, cyanuric acid trichloride,3,3′,4,4′-benzophenone-tetracarboxylic acid tetrachloride,1,4,5,8-naphthalenetetracarboxylic acid tetrachloride or pyromelliticacid tetrachloride, in amounts of from 0.01 to 1.0 mol % (based on thedicarboxylic acid dichlorides employed), or phenols which aretrifunctional or more than trifunctional, such as phloroglucinol,4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-hept-2-ene,4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane,1,3,5-tri(4-hydroxyphenyl)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane,tri-(4-hydroxyphenyl)phenylmethane,2,2-bis-[4,4-bis-(4-hydroxyphenyl)-cyclohexyl]-propane,2,4-bis-(4-hydroxyphenyl-isopropyl)-phenol,tetra-(4-hydroxyphenyl)-methane,2,6-bis-(2-hydroxy-5-methyl-benzyl)-4-methyl-phenol,2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)-propane,tetra-(4-[4-hydroxyphenyl-isopropyl]-phenoxy)-methane and1,4-bis-[4,4′-dihydroxy-triphenyl)methyl-]benzene, in amounts of from0.01 to 1.0 mol-%, based on the diphenols employed. Phenolic branchingagents may be initially introduced into the reaction vessel with thediphenols, and acid chloride branching agents may be introduced togetherwith the acid dichlorides.

The content of carbonate structural units in the thermoplastic, aromaticpolyester carbonates may be varied as desired. In one aspect, thecontent of carbonate groups is up to 100 mol-%, in another aspect up to80 mol-%, in a further aspect up to 50 mol-%, based on the sum of estergroups and carbonate groups. Both the ester and the carbonate content ofthe aromatic polyester carbonates may be present in the polycondensatein the form of blocks or in random distribution.

The relative solution viscosity (η_(rel)) of the aromatic polycarbonatesand polyester carbonates is in the range of from 1.18 to 1.4, in anotheraspect 1.20 to 1.32 (measured on solutions of 0.5 g polycarbonate orpolyester carbonate in 100 ml methylene chloride solution at 25° C.).The thermoplastic, aromatic polycarbonates and polyester carbonates maybe employed by themselves, or in any desired mixture of one or more, orin another aspect one to three, or one or two thereof. In a furtheraspect only one type of polycarbonate is used.

In even another aspect the aromatic polycarbonate is a polycarbonatebased on bisphenol A and phosgene, which includes polycarbonates thathave been prepared from corresponding precursors or synthetic buildingblocks of bisphenol A and phosgene. These aromatic polycarbonates may belinear or branched due to the presence of branching sites.

Suitable polyamides are known homopolyamides, copolyamides and mixturesof such polyamides. They may be semi-crystalline and/or amorphouspolyamides. Suitable semi-crystalline polyamides are polyamide-6,polyamide-6,6, mixtures and corresponding copolymers of thosecomponents. Also included are semi-crystalline polyamides the acidcomponent of which consists wholly or partially of terephthalic acidand/or isophthalic acid and/or suberic acid and/or sebacic acid and/orazelaic acid and/or adipic acid and/or cyclohexanedicarboxylic acid, thediamine component of which consists wholly or partially of m- and/orp-xylylene-diamine and/or hexamethylenediamine and/or2,2,4-trimethylhexamethylenediamine and/or2,2,4-trimethylhexamethylenediamine and/or isophoronediamine, and thecomposition of which is in principle known.

Mention may also be made of polyamides that are prepared wholly orpartially from lactams having from 7 to 12 carbon atoms in the ring,optionally with the concomitant use of one or more of theabove-mentioned starting components.

In another aspect semi-crystalline polyamides are polyamide-6 andpolyamide-6,6 and mixtures thereof. Known products may be used asamorphous polyamides. They are obtained by polycondensation of diamines,such as ethylenediamine, hexamethylenediamine, decamethylenediamine,2,2,4- and/or 2,4,4-trimethylhexamethylenediamine, m- and/or p-xylylenediamine, bis-(4-aminocyclohexyl)-methane,bis-(4-aminocyclohexyl)-propane,3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane,3-aminomethyl-3,5,5-trimethylcyclohexylamine, 2,5- and/or2,6-bis-(aminomethyl)-norbornane and/or 1,4-diaminomethylcyclohexane,with dicarboxylic acids such as oxalic acid, adipic acid, azelaic acid,azelaic acid, decanedi-carboxylic acid, heptadecanedicarboxylic acid,2,2,4- and/or 2,4,4-trimethyladipic acid, isophthalic acid andterephthalic acid. Also suitable are copolymers obtained bypoly-condensation of a plurality of monomers, as well as copolymersprepared with the addi-tion of aminocarboxylic acids such asε-aminocaproic acid, ω-aminoundecanoic acid or ω-aminolauric acid ortheir lactams.

In a further aspect suitable amorphous polyamides are the polyamidesprepared from isophthalic acid, hexamethylenediamine and furtherdi-amines such as 4,4′-diamino-dicyclohexylmethane, isophoronediamine,2,2,4- and/or 2,4,4-trimethylhexamethylenediamine, 2,5- and/or2,6-bis-(aminomethyl)-norbornene; or from isophthalic acid,4,4′-diamino-dicyclohexylmethane and ε-caprolactam; or from isophthalicacid, 3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane and laurinlactam;or from terephthalic acid and the isomeric mixture of 2,2,4- and/or2,4,4-trimethylhexamethylenediamine. Instead of pure4,4′-diaminodicyclohexylmethane it is also possible to use mixtures ofthe position-isomeric diaminodicyclohexylmethanes, which are composed offrom 70 to 99 mol-% of the 4,4′-diamino isomer, of from 1 to 30 mol-% ofthe 2,4′-diamino isomer, of from 0 to 2 mol-% of the 2,2′-diamino isomerand optionally corresponding to more highly condensed diamines, whichare obtained by hydrogenation of industrial gradediaminodiphenylmethane. Up to 30% of the isophthalic acid may bereplaced by terephthalic acid.

In one aspect, the polyamides have a relative viscosity (measured on a 1wt.-% solution in m-cresol or 1% (weight/volume) solution in 96 wt.-%sulfuric acid at 25° C.) of from 2.0 to 5.0, in a further aspect of from2.5 to 4.0.

The pigment component B is used for coloring the thermoplastic resincomposition either by at least one colorant or at least one pigment.

Examples for suitable colorants include all dyes that may be used fortransparent, semi-transparent, or non-transparent coloring of styrenecopolymers. Any pigment suitable for this purpose can be used. Pigmentsare either organic or inorganic pigments. Examples for suitable pigmentsinclude titanium dioxide, phthalocyanines, ultramarine blue, ironoxides, carbon black, and the entire class of organic pigments. In oneaspect of the present invention pigment B is an inorganic pigment. Inanother aspect of the present invention, pigment B is a metal-basedpigment. In a further aspect of the present invention, pigment B is atransition metal based pigment. In a preferred aspect of the presentinvention, iron based pigments such as iron oxide based pigments areused.

The at least one UV light stabilizer C is selected from hindered amineUV light stabilizers (HALS). In one aspect of the present invention, thethermoplastic resin composition according to any of the previous claims,wherein component C is a hindered amine UV light stabilizer according tothe following formula (Ia) and/or formula (Ib):

wherein R1 is H or methyl; each R2 is individually selected from thegroup consisting of hydrogen, methyl, and ethyl; R3 is selected from thegroup consisting of linear C₁- to C₁₈-esters which are connected toformula (Ia) via the oxygen atom of the ester function; and with R4being selected from the group consisting of C1 to C10 alkylene.

In another aspect of the present invention, the HALS component C isselected from the group consisting of a compound according to formula(II), a compound according to formula (III), and mixtures thereof.

This sterically hindered amine according to formula (II) (CAS Number52829-07-9) and its preparation are known to the skilled person anddescribed in the literature (see, for example, U.S. Pat. No. 4,396,769and the literature references cited therein). It is sold by BASF SEunder the Tinuvin® 770 name.

The sterically hindered amine according to formula (III) (CAS Number167078-06-0) and its preparation from 2,2,6,6-tetra-methyl-4-piperinoland stearic and/or palmitic acid are known to the skilled person anddescribed in the literature (Carlsson et al., Can. Journal of PolymerScience, Polymer Chemistry Edition (1982), 20(2), 575-82). It is sold byCytec Industries under the Cyasorb® 3853 name.

Another example for hindered amine UV light stabilizers are compoundsformula (IV):

This sterically hindered amine (CAS Number 71878-19-8) and itspreparation are known to the skilled worker and described in theliterature (see, for example, EP-A 093 693 and the literature referencescited therein). It is sold by BASF SE under the Chimassorb® 944 name.

A further example for a hindered amine UV light stabilizer is thecompound of the formula (V):

In this formula, n is of from 2 to 25. In another aspect of theinvention n is of from 2 to 20. In a further aspect n is of from 2 to15.

This sterically hindered amine (CAS Number 101357-37-3) and itspreparation are known to the skilled worker and described in theliterature (see U.S. Pat. No. 5,208,132 and the literature referencescited therein). It is sold by ADEKA under the Adeka Stab® LA-68 name.

A further example for a hindered amine UV light stabilizer is thecompound of the formula (VI):

In this formula, n is of from 2 to 25. In another aspect of theinvention n is of from 2 to 20. In a further aspect n is of from 2 to15.

This sterically hindered amine (CAS Number 82451-48-7) and itspreparation are known to the skilled worker and described in theliterature (see, for example, U.S. Pat. No. 4,331,586 and the literaturereferences cited therein). It is sold by Cytec Industries under theCyasorb® UV-3346 name.

A further example for a hindered amine UV light stabilizer is thecompound of the formula (VII):

In this formula, n is of from 2 to 25. In another aspect of theinvention n is of from 2 to 20. In a further aspect n is of from 2 to15.

This sterically hindered amine (CAS Number 192268-64-7) and itspreparation are known to the skilled worker and described in theliterature (see, for example, EP-A 782 994 and the literature referencescited therein). It is sold by BASF under the Chimassorb® 2020 name.

In all aspects of the present invention, only hindered amine UV lightstabilizers C are present in the thermoplastic resin composition. Thisis to be understood that less than 10 wt.-% of UV stabilizers orabsorbers based on the total weight of UV stabilizers C other than UVstabilizers of the HALS class are present in the thermoplastic resincomposition of the present invention. In another aspect of the presentinvention, only 2 wt. % of UV stabilizers or absorbers based on thetotal weight of UV stabilizers C other than UV stabilizers of the HALSclass are present in the thermoplastic resin composition of the presentinvention. In a further aspect less than 0.1 wt.-% of UV stabilizers orabsorbers based on the total weight of UV stabilizers C other than UVstabilizers of the HALS class are present in the thermoplastic resincomposition of the present invention.

If present, the at least one polymer additive D is selected from thegroup consisting of oxidation retarders, agents to counter thermaldecomposition, lubricants and mold release agents, fibrous andpulverulent fillers, reinforcing agents, nucleating agents, metalscavengers and plasticizers. Polymer additives D are different from anycomponent B and C.

Examples of oxidation retarders and heat stabilizers are halides of themetals from group I of the periodic table, examples being sodium,potassium and/or lithium halides, optionally in combination withcopper(I) halides, e.g., chlorides, bromides, iodides, stericallyhindered phenols, hydroquinones, different substituted representativesof these groups, and mixtures thereof, in concentrations of up to 1wt.-%, based on the weight of the polymer blend according to the presentinvention.

Furthermore fibrous and pulverulent fillers and reinforcing agents areused. Examples of the latter are carbon fibers, glass fibers, amorphoussilica, calcium silicate (wollastonite), aluminum silicate, magnesiumcarbonate, kaolin, chalk, powdered quartz, mica, and feldspar.

Examples of nucleating agents that can be used are talc, calciumchloride, sodium phenylphosphinate, aluminum oxide, and silicon dioxide.

Examples of lubricants and mold release agents, which can be used ingeneral in amounts up to 1 wt.-%, are long-chain fatty acids such asstearic acid or behenic acid, their salts (e.g., Ca or Zn stearate) oresters (e.g., stearyl stearate or pentaerythrityl tetrastearate), andalso amide derivatives (e.g., ethylenebisstearylamide). For betterprocessing, mineral-based antiblocking agents may be added in amounts upto 0.1 wt. % to the molding compositions of the invention. Examplesinclude amorphous or crystalline silica, calcium carbonate, or aluminumsilicate.

Processing aids which can be used are, for example, mineral oil such aswhite oil.

Examples of plasticizers include dioctyl phthalate, dibenzyl phthalate,butyl benzyl phthalate, hydrocarbon oils, N-(n-butyl)benzenesulfonamide,and o- and p-tolylethylsulfonamide.

For further improving the resistance to inflammation, it is possible toadd all of the flame retardants known for the thermoplastics inquestion, more particularly those flame retardants based on phosphoruscompounds and/or on red phosphorus itself.

In one aspect of the present invention the thermoplastic resincomposition comprises at least one component D which is a metalscavenger. Metal scavengers are characterized in that they comprisereactive ligands which are capable of complexing metal ions. Thereactive ligands may be attached to a small molecule or to a polymeric,often inert backbone. In one embodiment of the present invention, themetal scavenger component D comprises at least one hydrazide group. In afurther aspect of the present invention, the metal scavenger component Dis a component according to formula (VIII):

wherein R15 and R16 are independently from each other selected from alinear or branched C₂- to C₁₀-alkanediylgroup, R5 to R14 areindependently from each other selected from the group consisting ofhydrogen, a linear or branched C₁- to C₁₀-alkyl group, an amine group,an either monosubstituted or disubstituted, linear or branched C₁- toC₁₀-monoamine or diamine, a hydroxyl group, an alkoxy group with alinear or branched C₁- to C₁₀-alkyl group, a carboxylic group, an estergroup with a linear or branched C₁- to C₁₀-alkyl group, a thiol, amercaptane with a linear or branched C₁- to C₁₀-alkyl group. In oneaspect of the present invention, R5 to R14 are independently from eachother selected from the group consisting of hydrogen, a linear orbranched C₁- to C₁₀-alkyl group, and a hydroxyl group. In a furtheraspect of the present invention, R5 to R14 are independently from eachother selected from the group consisting of linear or branched C₂- toC₈-alkyl group. In even another aspect of the present invention, R5 toR14 are independently from each other selected from the group consistingof linear or branched C₂- to C₅-alkyl group.

In a further aspect R5, R9, R10, and R14 are independently from eachother hydrogen or methyl, R6, R8, R11, R13 are independently from eachother C₂- to C₈-alkyl, and R7, and R12 are independently from each otherhydroxy or C₁- to C₁₀-alkoxy groups. In a further aspect R5, R9, R10,and R14 are hydrogen, R6, R8, R11, R13 are tert.-butyl, and R7, and R12are hydroxy groups.

In another aspect, the metal scavenger D is the compound according toformula IX:

The thermoplastic resin composition according to the present inventionshow improved resistance under artificial weathering conditions. Thiscan for example be quantified by applying standardized artificialweathering tests as disclosed in DIN ISO-4892-2 or DIN ISO 4892-3 bycomparing the color shift dE of inventive samples and of comparativesamples. This is for example done after 6000 h of artificial weathering.In one aspect of the present invention the composition shows a colorshift dE of equal to or lower than 3.0 upon UV irradiation according toISO-4892-2 after 6000 hours. In a further aspect of the presentinvention the composition shows a color shift dE of equal to or lowerthan 2.0 upon UV irradiation according to ISO-4892-2 after 6000 hours.

In another aspect of the present invention the composition shows a colorshift dE of equal to or lower than 1.5 upon UV irradiation according toISO-4892-2 after 6000 hours.

In one aspect the composition shows a color shift dE of equal to orlower than 2.5 upon UV irradiation according to ISO-4892-3 after 6000hours. In another aspect the composition shows a color shift dE of equalto or lower than 2.0 upon UV irradiation according to ISO-4892-3 after6000 hours. In a further aspect the composition shows a color shift dEof equal to or lower than 1.5 upon UV irradiation according toISO-4892-3 after 6000 hours.

The color shift dE was calculated as disclosed in DIN ISO-5033-2 with aDatacolor spectral photometer 110.

The present invention further relates to a method for the preparation ofthe thermoplastic resin composition according to the invention.

The thermoplastic resin composition according to the invention cangenerally be obtained by any usual method, comprising the step of mixingcomponents A1, A2, B, C, and optionally A3 and D at temperatures of from100° C. to 300° C. and a pressure of from 1 to 150 bar, e.g. in randomorder, followed by a kneading or extrusion step.

Mixing apparatuses used are those known to the skilled person.Components A1, A2, B, C, and optionally A3 and D may be mixed, forexample, by joint extrusion, kneading, or rolling.

Examples of mixing apparatus for implementing the method includesdiscontinuously operating, heated internal kneading devices with orwithout ram-feeder, continuously operating kneaders, such as continuousinternal kneaders, screw kneaders with axially oscillating screws,Banbury kneaders, furthermore extruders, and also roll mills, mixingroll mills with heated rollers, and calenders. In one aspect of theinvention, the mixing apparatus used is an extruder. Particularlysuitable for melt extrusion are, for example, single-screw or twin-screwextruders. In a further aspect of the invention a twin-screw extruder isused.

In some cases the mechanical energy introduced by the mixing apparatusin the course of mixing is enough to cause the mixture to melt, meaningthat the mixing apparatus does not have to be heated. Otherwise, themixing apparatus is generally heated.

The temperature is guided by the chemical and physical properties ofcomponents A1, A2, B, C, and optionally A3 and D, and should be selectedsuch as to result in a substantially liquid-melt polymer mixture. On theother hand, the temperature is not to be unnecessarily high, in order toprevent thermal damage of the polymer mixture.

The mechanical energy introduced may, however, also be high enough thatthe mixing apparatus may even require cooling. Mixing apparatus isoperated customarily at of from 160 to 400° C., in another aspect offrom 180 to 300° C.

In one aspect of the invention, mixing can be performed for example byjoint extrusion and calendering. The calendering is expediently carriedout firstly in kneaders or extruders (softening) and, if desired, onmixing rolls, followed by the actual calendering process with, ifdesired, addition of suitable stabilizers. Blowmolding and injectionmolding are carried out on the usual machinery.

In one aspect of the invention, the extrusion of the thermoplastic resincomposition according to the present invention is carried out in anextruder at a temperature above 100° C. In another aspect of the presentinvention the feeding zone of the single- or twin-screw extruder is setto a temperature in the range of from 100 to 180° C., themixing/kneading zones to of from 180 to 250° C. and the final zones toof from 220 to 270° C. Nozzle temperature is set to a temperature in therange of from 240 to 280° C. In a further aspect, the nozzle temperatureis set to a temperature in the range of from 255 to 265° C. Tooltemperature is set to a temperature in the range of from 50 to 100° C.In one aspect of the invention, tool temperature is set in the range offrom 60 to 80° C. Screw speed is set in the range of from 300 to 500rpm. Injection pressure is set in the range of from 50 to 120 bar. Inanother aspect of the invention, injection pressure was set in the rangeof from 80 to 110 bar.

For workup the extruder can be equipped with a hole-plate, water-bathand pelletizer for making pellets or micro-pellets.

Another aspect of the present invention is related to the method forpreparation the thermoplastic resin composition according to the presentinvention wherein at least two of components A1, A2, B, C, andoptionally A3 and D are premixed to form a masterbatch.

Another aspect of the invention relates to the use of the thermoplasticresin composition for the preparation of molded articles, such asarticles used for cars or electronic devices.

A further aspect of the invention relates to molded articles preparedfrom the thermoplastic resin composition according the presentinvention.

The molded article can be used in various fields of applications such ashousehold items, electronic components, household equipment, gardenequipment, medicaltechnology equipment, automotive parts, motor-vehiclecomponents, building and construction, and bodywork parts. In anotheraspect the polymer blend as described above can be used for theproduction by injection molding of a automotive part, a household part,wall sidings, or roof tiles.

The following examples and claims further illustrate the invention.

Raw Materials

Luran® S 776 SE is a commercially available ASA copolymer from INEOSStyrolution (Frankfurt).

Palatinol 10-P (phthalic acid ester of C10 alcohols) can be purchasedfrom BASF SE. Colortherm Red 110M is a micronized iron oxid red pigment,commercially available by Supplier Lanxess (Germany), produced accordingto Laux process.

Tinuvin P (2-(2H-benzotriazol-2-yl)-p-cresol, CAS-No. 2440-22-4) is acommercial UV-absorber that can be purchased from BASF SE. Tinuvin® 770(Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, CAS-No. 52829-07-9) canbe purchased from BASF SE.

Sample Preparation

For compounding a Coperion ZSK 25 extruder was used and for injectionmolding an Arburg machine. All test specimens have the followingdimensions: 75×50 mm.

Testing

Artificial weathering according to ISO 4892-2A(1) was conducted underthe following conditions:

Irradiance wavelength nm 300 to 400 340 Light strength W/m² 60 ± 2  0.51± 0.02 Black board temperature ° C. 65 ± 3  Relative humidity % 50 ± 10Cycle time for Duration for min  18 water spray water spray Duration fornot min 102 water spray Xenon filter Inner — Boro. S. (S-type)combination outer — Boro. S. (S-type)

For artificial weathering according to ISO 4892-3 a Q-UVse testerequipped with UVA-340 lamps was used. Each cycle consists of 8 hirradiation (0.76 W/m², 60° C. black panel temperature) and 4 hcondensation (no irradiation, 50° C. black panel temperature).

For color measurements a commercial testing device Datacolor 110 wasused.

EXAMPLES

Commercially available ASA-copolymer Luran S 776SE was compounded withthe pigment Colortherm Red 110M, the plasticizer Palatinol 10-P anddifferent amounts of UV stabilizers (HALS and UV absorbers (comparativeexamples only)).

The formulations without UV absorber showed the best results regardingcolor shift dE after artificial weathering as carried out describedfurther in below.

Samples have been tested according to two different artificialweathering methods: ISO 4892-2 and ISO 4892-3. Total color shift hasbeen measured every 1000 h.

According to both methods the thermoplastic resin according to thepresent invention containing only a HALS as UV stabilizer (Tinuvin 770)yielded always the lowest color shift.

Comparative Comparative Example Example Example 1 (B) 1 (C) 2 (K)Component A (thermoplastic 96.15 96.15 96.15 resin) Luran S 776SEComponent D (additive) 1.44 1.44 1.44 Palatinol 10-P Component B(Pigment) 1.92 1.92 1.92 Iron Oxide Red01 Colortherm Red 110M ComponentC (HALS) 0.48 0.48 Tinuvin 770 UV absorber Tinuvin P 0.48 0.48 dE after4000 h (ISO 0.61 7.13 3.12 4892-2) dE after 5000 h (ISO 0.68 8.27 —4892-2) dE after 6000 h (ISO 1.07 8.39 3.04 4892-2) dE after 5000 h (ISO1 2 3.4 4892-3) dE after 6000 h (ISO 1.2 2.5 4.3 4892-3)

The invention claimed is:
 1. A thermoplastic resin compositioncomprising: (a1) at least one styrene-acrylonitrile copolymer componentA1, (a2) at least one acrylonitrile styrene acrylate graft copolymer A2as impact modifier, (a3) optionally at least one thermoplastic polymerA3 other than components A1 and A2, (b) at least one transition metalpigment B, (c) one hindered amine UV light stabilizer C, and (d)optionally further polymer additives D, other than components B and C,wherein the hindered amine UV light stabilizer C is the only UVstabilizing component present in the thermoplastic resin, and whereinthe composition shows a color shift dE of equal to or lower than 3.0upon UV irradiation according to ISO-4892-2 after 6000 hours.
 2. Thethermoplastic resin composition according to claim 1, comprising 70.0 to99.4 wt.-%, based on the total weight of the composition, of componentsA1, A2, and optionally A3, and comprising 0.5 to 7.0 wt.-%, based on thetotal weight of the composition, of component B, and comprising 0.1 to1.5 wt.-% based on the total weight of the composition of component C.3. The thermoplastic resin composition according to claim 1, comprising(i) of from 89.0 to 99.3 wt.-%, based on the total weight of thecomposition, of A1, A2, and optionally A3, (ii) of from 0.5 to 7.0wt.-%, based on the total weight of the composition, of component B,(iii) of from 0.1 to 1.5 wt.-%, based on the total weight of thecomposition, of the hindered amine UV light stabilizer C, and (iv) offrom 0.1 to 2.5 wt.-%, based on the total weight of the composition, ofat least one further polymer additive D.
 4. The thermoplastic resincomposition according to claim 1, wherein the styrene-acrylonitrilecopolymer component A1 has an acrylonitrile content of from 5 to 35wt.-% based on the total weight of the styrene-acrylonitrile copolymercomponent A1.
 5. The thermoplastic resin composition according to claim1, wherein the impact-modified graft rubber acrylonitrile styreneacrylate A2 comprises: a graft base A2.1 of from 40 to 90 wt.-% based onthe total weight of the impact-modified graft rubber acrylonitrilestyrene acrylate A2 comprising: (i) from 70 to 99.9 wt.-% of n-butylacrylate based on the total weight of A2.1, (ii) from 0 to 30 wt.-% ofstyrene based on the total weight of A2.1, and (iii) from 0.1 to 5 wt.-%of a crosslinking agent based on the total weight of A2.1; and a graftA2.2 of from 10 to 60 wt.-% comprising: (iv) from 65 to 95 wt.-% basedon the total weight of A2.2 of styrene, and (v) from 5 to 35 wt.-% basedon the total weight of A2.2 of acrylonitrile.
 6. The thermoplastic resincomposition according to claim 1, comprising from 1 to 70 wt.-% based onthe total weight of components A1 and A2 of at least one thermoplasticpolymer A3 selected from the group consisting of polycarbonate (PC),polyamide (PA), and mixtures thereof.
 7. The thermoplastic resincomposition according to claim 1, wherein the component C is a hinderedamine UV light stabilizer according to the following formula (Ia) orformula (Ib):

wherein R1 is H or methyl; each R2 is individually selected from thegroup consisting of hydrogen, methyl, and ethyl; R3 is selected from thegroup consisting of linear C1- to C18-esters which are connected toformula (Ia) via the oxygen atom of the ester function; and with R4being selected from the group consisting of C1 to C10 alkylene.
 8. Thethermoplastic resin composition according to claim 7, wherein thecomponent C is selected from the group consisting of a compoundaccording to formula (II) or a compound according to formula (III),


9. The thermoplastic resin composition according to claim 1, wherein atleast one component D is a metal scavenger.
 10. The thermoplastic resincomposition according to claim 1, wherein the composition shows a colorshift dE of equal to or lower than 2.5 upon UV irradiation according toISO-4892-3 after 6000 hours.
 11. The thermoplastic resin compositionaccording to claim 1, comprising a plasticizer as component D.
 12. Thethermoplastic resin composition according to claim 11, wherein theplasticizer is selected from phthalic acid esters of C10 alcohols,dioctyl phthalate, dibenzyl phthalate, butyl benzyl phthalate,N-(n-butyl)benzenesulfonamide, and o- and p-tolylethylsulfonamide.
 13. Amethod for preparing the thermoplastic resin composition according toclaim 1, comprising the step of mixing A1, A2, B, C, and optionally A3and D, at temperatures of from 100° C. to 300° C. and a pressure of from1 to 150 bar, in any order, followed by a kneading or extrusion step.14. The method for preparing the thermoplastic resin compositionaccording to claim 13, wherein at least two of components A1, A2, B, C,and optionally A3 and D, are premixed to form a masterbatch.
 15. Amolded article prepared from the thermoplastic resin compositionaccording to claim 1.